This invention relates generally to the field of ophthalmologic surgery and more particularly to an apparatus and methods for removing cataracts.
The human eye functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens.
When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light that can be transmitted to the retina. This deficiency is medically known as a cataract. An accepted treatment for cataracts is to surgically remove the cataract and replace the lens with an artificial intraocular lens (IOL). In the United States, the majority of cataractous lenses are removed using a surgical technique called phacoemulsification. During this procedure, a thin needle with a distal cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquefies or emulsifies the lens so that the lens may be aspirated from the eye. The diseased lens, once removed, is replaced by an artificial intraocular lens (IOL).
A typical ultrasonic surgical device suitable for an ophthalmic procedure includes an ultrasonically driven hand piece, an attached cutting tip, an irrigating sleeve and an electronic control console. A liquefaction hand piece may also be used. The hand piece assembly is attached to the control console by an electric cable or connector and flexible tubing. A surgeon controls the amount of ultrasound power that is delivered to the cutting tip of the hand piece and applied to tissue at any given time by depressing a foot pedal. Flexible tubing supplies irrigation fluid to and draws aspiration fluid from the eye through the hand piece assembly. Typically, this flexible tubing has a single degree of pliability or hardness. The inventors have discovered that varying this degree of pliability or hardness provides benefits over traditional tubing.